Direct mount or adapter plate?
By Andrew Terrebonne. Published October 12, 2026.
Of the 6,927 pistol and optic pairs here that mount at all, 1,678 go straight onto the slide, 1,250 need a plate that already ships with the pistol or the optic, and 3,999 need a plate you buy. This guide shows what that choice does to the price and what it does to the stack.
| Route | Pairs | Typical cost to mount | Typical plate cost |
|---|---|---|---|
| Direct to the slide | 1,678 | $150–$300 | — |
| Plate in the box | 1,250 | $150–$300 | in the box |
| Plate you buy | 3,999 | $313–$475 | $25–$60 |
Median of each pair’s low and high price band, approximate street prices checked September 2026. A pair’s own page has its exact band. The pairs are every pistol against every optic, not what people actually buy, so treat the medians as a comparison between routes, not a budget.
Three real pairs
One of each route, with the price band the pair’s own page gives:
| Route | Pair | Cost to mount | Plate |
|---|---|---|---|
| Direct to the slide | Holosun 507K X2 on the SIG Sauer P365XL | $300–$450 | none |
| Plate in the box | Holosun 507C X2 on the GLOCK 19 Gen5 MOS | $300–$450 | in the box |
| Plate you buy | Holosun 507C X2 on the GLOCK 43X MOS | $325–$510 | $25–60 |
What a plate adds
- A joint. A plate means two sets of screws, one holding the plate to the slide and one holding the optic to the plate, each with its own thread and torque. A direct mount has one. The fit checker’s build sheet lists both, and pair pages give each joint its own source.
- Height. The optic sits on top of the plate, so its window sits higher over the slide. The co-witness verdicts reflect this. For an open-emitter optic with suppressor-height irons, the fit checker says “Co-witnesses” on a direct cut and “Usually a low co-witness” on a plate (why).
- A part to match. A plate has to carry your optic’s footprint and fit your slide’s cut. The GLOCK MOS guide shows what that looks like for one family.
When a plate is the only way
Many slides are cut for one footprint, and the optics on the others reach them only through a plate. If you want a particular optic, its footprint’s reach tells you how many slides take it with and without one. Where a slide has no plate for a footprint at all, the pair page says “no known fit” rather than suggest a workaround.
Whichever route you choose, the install guide collects what the makers say about screws, threadlocker and torque, and the lost-zero guide is where to look if the mount works loose.